Macbook pro 2011 battery dropped to 30% after 300 cycles

Question

Hello ,
I have a Macbook pro early 2011 and I have noticed that the battery suddenly is draining too fast , after installing battery health it seems that in 2 weeks the battery dropped from 86% to 30% and there is the service battery sign
Please help !
Charge Information:
  Charge Remaining (mAh):    1696
  Fully Charged:    Yes
  Charging:    No
  Full Charge Capacity (mAh):    1696
  Health Information:
  Cycle Count:    304
  Condition:    Service Battery
  Battery Installed:    Yes
  Amperage (mA):    -133
  Voltage (mV):    11953

Answer 1

Cycles mean almost NOTHING,  its short term abuse that matters.
1. did you often drain the battery very low?
2. did you often /always have your macbook on charge,......or did you often / always BOTH have your macbook on charge AND in sleep mode?
3. did you often /always play realistic heavy graphics games ON battery on your notebook?
1 or 2 and 3 are harsh on the battery chemistry and therefore its longevity
all batteries are consumables meant to replaced either in their own "due time" or early due to abuse / misuse.
Proper understanding of a battery charge cycle
A charge cycle means using all of the battery’s power, whether that is at once, or over several shorter battery discharges and recharges.
Two examples for clarification:
As a first example, where one fully charged battery is discharged down to 10%, then fully recharged, then using 10% of that full charge, this counts as 1 cycle since the total of both discharges is 100% of a full charge of use.
In the second example, where one fully charged battery is discharged down to 40%, then fully recharged, then using 40% of that full charge, this also counts as 1 cycle since the total of both discharges is 100% of a full charge of use.
While both examples are that of a single charge cycle, the first example is more aggressive against the lithium battery chemistry than is the second example. In short, collective overall gentle shallow or mid-range draining of your lithium battery is a better use condition than is the first example of deep-draining of the battery.  While both are quantitatively identical as a single charging cycle, they are wholly different qualitatively on the battery chemistry, which is directly related to its ultimate longevity and health.
In short, it is the near and mid-term life of the battery as relates to its proper care (or lack thereof) that is to be looked after.
Priorities in order of decreasing importance for battery care are:
1. Avoiding deep discharges of the battery.
2. Avoiding having your battery constantly on charge or on charge and in sleep mode.
3. When playing graphics intense games, use your notebook plugged in when possible.
4. Reduction of battery cycles by plugging into power when on the go, or when accessible.
A person who has, for example, 300 charge cycles on their battery and is recharging at say 40% remaining of a 100% charge has a better battery condition state than, say, another person who has 300 charge cycles on their battery and is recharging at say 10-15% remaining on a 100% charge. DoD (depth of discharge) is vitally important on the wear and tear on your Macbook’s battery, much more so than is the counting of charge cycles. There is no set “mile” or wear from a charge cycle in specific. Frequent high depth of discharge rates (draining the battery very low) on a Lithium battery will greatly hasten the lowering of maximum battery capacity.
Understand that a charge cycle is a general parameter of use, but is not directly related to the short-term or mid-term abuse of the battery, which can rapidly hasten a shorter lifespan, regardless of what the actual cycle count on the battery indicates.
Proper considerations for near-term care of the battery is of utmost importance. Abuse of the battery is entirely avoidable, long-term eventual old age deterioration of the battery is entirely unavoidable.
Apple’s adaptive charging system mitigates much potential for accidental battery misuse or abuse; however it is still readily possible to abuse the battery and thereby affect battery health.